The present invention relates to gas turbine engines, and in particular, to a fuel system for a gas turbine engine. Gas turbine engines typically include one or more fuel manifolds that receive fuel from a main fuel tank and deliver that fuel to a combustor section for combustion. When the gas turbine engine is shut down, fuel remaining in the fuel manifold can drain into the combustion chamber, and ultimately evaporate and/or drain out of the gas turbine engine onto the ground. This can be undesirable for ecological reasons.
Some gas turbine engines include an ecology tank for storing fuel from the fuel manifold after engine shut down. Such systems typically include a number of components, such as an ejector pump, check valves, vents, plumbing, and the ejector tank. These components can undesirably increase the cost, complexity, and weight of the fuel system. Some gas turbine engines drain fuel from the fuel manifold and send it back to the main fuel tank. But a main inlet line from the fuel tank to one or more pumps often has a check valve or pilot-operated valve preventing backflow during shutdown, keeping the pumps primed with fuel. These engines can drain fuel manifolds by using a second plumbing line from the fuel manifold back to the fuel tank. This second plumbing line often has a second function of sending excess fuel back to the fuel tank to assist in pressurizing the fuel inlet line for improved pump performance. But not all aircraft have a second plumbing line returning to the fuel tank for various functional and operation reasons.